The invention relates to novel hydroxypyridonemethide azo dyes, processes for their preparation and their use and also dye mixtures containing hydroxypyridonemethide azo dyes. EP-A 767 220 already discloses similar azo dyes. These dyes, however, are still in need of improvement with regard to their application properties, especially their thermomigration fastness.
Novel hydroxypyridonemethide azo dyes have been found that, surprisingly, are notable for excellent thermomigration fastness and sublimation fastness coupled with good general fastnesses.
The present invention provides novel hydroxypyridonemethide azo dyes conforming to the formula (I) or its tautomeric forms 
where
X1 is H, Cl, Br, xe2x80x94CN, xe2x80x94CHxe2x95x90O, xe2x80x94COxe2x80x94T, xe2x80x94CO2xe2x80x94R2, xe2x80x94SO2xe2x80x94T, or xe2x80x94NO2,
X2, X3 and X4 are independently H, Cl or Br,
R1 is H, T, or xe2x80x94CF3, and
R2 is straight-chain or branched C1-C4-alkyl,
where
T is straight-chain or branched C1-C10-alkyl which may be interrupted by 1 or 2 oxygen atoms in ether function and/or substituted by one or more, preferably one, phenyl or hydroxyl radicals, or is phenyl which may be substituted by 1 to 2 identical or different radicals selected from the group consisting of Cl, Br and C1-C2-alkyl.
The dyes of the formula (I) can also exist in tautomeric forms, of which the most important is the formula (Ia) 
For the purposes of the present invention, the formula (I) in its general and preferred meanings includes all possible tautomeric forms, especially that of the formula (Ia).
Preference is given to hydroxypyridonemethide azo dyes of the formula (I) or (Ia) where
X2, X3 and X4 are each H.
Particular preference is given to dyes of the formulae (I) and (Ia), where
X2, X3 and X4 are each H,
R1 is H, xe2x80x94CH3, xe2x80x94C2H5, xe2x80x94CH(CH3)2, unsubstituted phenyl or CF3, and
R2 is CH3 or C2H5.
Very particular preference is given to dyes of the formula (I) where
x1 is H, Cl, Br, or xe2x80x94NO2,
X2, X3 and X4 are each H,
R1 is H, xe2x80x94CH3, xe2x80x94C2H5, or xe2x80x94CH(CH3)2, and
R2 is CH3 or xe2x80x94C2H5.
Preference is given in particular to dyes of the formula (I) where
X1 is nitro,
X2, X3 and X4 are each H,
R1 is H or CH3, and
R2 is CH3 or C2H5.
The dyes of the invention may be prepared, for example, by diazotizing an amine of the formula (II) 
where
X1, X2, X3 and X4 are each as defined above,
and coupling it onto a coupling component of the formula (III) 
where
R1 and R2 are each as defined above and
E is a substituent that is displaceable by electrophilic substitution, preferably by H, xe2x80x94CO2H, xe2x80x94CH2OH, xe2x80x94SO3H, xe2x80x94CHxe2x95x90O, xe2x80x94COT, xe2x80x94CONH2, xe2x80x94CONHT,
and where T is as defined above.
Such a coupling process by displacement of a substituent is described for example in GB-A 2036 775 and JP-A 58 157 863.
The coupling reaction may be carried out in aqueous and nonaqueous solvents. Nonaqueous solvents are alcohols such as methanol, ethanol, propanol, butanol, pentanol, etc., dipolar aprotic solvents such as DMF, DMSO, NMP and water-immiscible solvents such as toluene or chlorobenzene.
The coupling is preferably carried out in a stoichiometric ratio of coupling component and diazo component, although it may be advantageous and sensible, partly for economic reasons, to use the cheaper component in an excess of up to 30%.
The coupling is generally effected at temperatures between xe2x88x9230 to 100xc2x0 C., preference being given to temperatures of xe2x88x9210 to 30xc2x0 C., and particular preference to temperatures of xe2x88x925 to 10C.
The coupling may be carried out in an acidic as well as an alkaline medium. Preference is given to pH  less than 10, particular preference to pH  less than 7.0, very particular preference to pH  less than 5.0.
The diazo components of the formula (II) are literature known and partly also, like the particularly preferred 3-nitro-4-aminophenol, commercially available.
The coupling components of the formula (III) are likewise known and their preparation is described for example in EP-A 767 220.
The dyes of the formula (I) according to the invention are useful as such, mixed with each other or else mixed with other disperse dyes for dyeing and printing, including by the inkjet process, hydrophobic synthetic fiber materials and their blends with natural fiber materials.
Useful hydrophobic synthetic materials include for example secondary cellulose acetate, cellulose triacetate, polyamides and particularly polyesters, for example polyethylene glycol terephthalate. Examples of useful natural fiber materials are cotton, regenerated cellulose fibers and wool.
The dyes of the invention or mixtures thereof are also useful for coloring and printing waxes, oils and plastics such as polymethacrylate, PVC, polystyrene or ABS.
They are also useful for textile and nontextile thermal transfer printing, for example by means of a thermal head.
The coloring, dyeing and printing conditions, which include dyeing in supercritical carbon dioxide, are known per se, cf. for example EP-A 827 988, DE-A 3508 904 and EP-A 474 600.
The dyes of the invention or mixtures thereof can also be used for dyeing keratinic fibers, for example in hair dyeing or in the dyeing of furs.
The novel dyes of formula (I) or their mixtures are further very useful for producing color filters as described for example in EP-A-399 473.
Finally they are also useful as colorants for preparing toners for electrophotography.
The dyes of the invention or the mixtures thereof dye polyester in orange to violet shades having excellent thermomigration fastness and sublimation fastness, high color strength and a bright hue.
Particularly good affinity and build-up is provided by mixtures of the dyes of formula (I) which contain two or more, preferably two to 4, different dyes of the formula (I). Preference is given to mixtures which differ in the R1 and/or R2 substituents.
The present invention further provides dye mixtures containing at least one dye of the formula (I) and also at least one further disperse dye. Useful disperse dyes are the disperse dyes listed in the Color Index, especially benzodifuranone dyes, and also the disperse dyes known from EP-A 767 220.
Benzodifuranone dyes which are preferentially suitable as mixture dyes are derived from the formula (IV) 
where
Y1 and Y2 are independently H, C1-C6-alkoxy, with or without C1-C4-alkoxycarbonyl, C1-C4-alkoxy-C2-C4-alkoxycarbonyl or furfuryl substitution, xe2x80x94OC2H4xe2x80x94Oxe2x80x94C1-C4-alkyl or xe2x80x94OC2H4xe2x80x94Oxe2x80x94(C2H4O)1-6xe2x80x94C1-C4-alkyl.
Of these, the following may be mentioned in particular:
(IVa) Y1=OCH2CH2CH3, Y2=H
(IVb) 
xe2x80x83Y2xe2x95x90H
(IVc) Y1=OCH2CH2CH3, Y2=OCH2CO2C2H4OC2H5 
(IVd) Y1=H, Y2=OCH2CO2C2H4OC2H5 
Preference is given to dye mixtures containing at least one dye of the formula (I) and at least one dye of the formula (IV).
Preference is further given to dye mixtures containing at least one dye of the formula (I) and at least one disperse dye of the formula (V) 
where
D is the radical of a carbo- or heterocyclic diazo component,
A1 and A2 are independently H or a typical pyridone substituent,
A5 is H, a radical of the formula T, xe2x80x94OT1, xe2x80x94NH2, xe2x80x94NHT, xe2x80x94NT2, xe2x80x94NHCOH, xe2x80x94NHCOT, xe2x80x94Nxe2x95x90CHxe2x80x94T,xe2x80x94Nxe2x95x90CT2 or xe2x80x94NHSO2T,
or
A1 and A2 and/or
A2 and A3 and/or
A4 and A5 combine with the atoms in between in each case to form an unsaturated, substituted or unsubstituted 5- or 6-membered carbo- or heterocycle, with the proviso that in the event of ring formation by participation of one of A3 and A4 the nonparticipant radical is an electron-attracting radical,
X is O, NH, NT, NCOT, NCO2T or NSO2T,
A3 and A4 are independently xe2x80x94CN, xe2x80x94CO2T, xe2x80x94CONH2, xe2x80x94CONHT, xe2x80x94CONT2, CF3, xe2x80x94CHO, xe2x80x94COT, xe2x80x94SO2T, xe2x80x94SO3T4, xe2x80x94SO3T5, SO2NH2, SO2NHT, SO2NT2, xe2x80x94SOT, xe2x80x94CHxe2x95x90NH, xe2x80x94CHxe2x95x90NT, xe2x80x94CTxe2x95x90NH, xe2x80x94CTxe2x95x90NT, 
xe2x80x83xe2x80x94COxe2x80x94CO2T, xe2x80x94NO2, xe2x80x94NO, or T4 T5 
but A3 and A4 are preferably not both T4 and/or T5 
or
A3 and A4 combine with the carbon atom to which they are attached to form a cyclic active-methylene compound of the formula (VIa) to (VIv), these radicals being specified in the form of 
where
V1 is H or a substituent, especially Cl, Br, CH3, xe2x80x94CO2T1, xe2x80x94CN, xe2x80x94NO2, xe2x80x94CF3 or xe2x80x94SO2T1, and
where
T is T1 to T5, where
T1 is alkyl, cycloalkyl or aralkyl,
T2 is alkenyl,
T3 is alkynyl,
T4 is aryl and
T5 is hetaryl.
In particularly preferred disperse dyes of the formula (V)
A1 is H, T1, T4 or xe2x80x94CF3,
A2 is H, xe2x80x94CN, xe2x80x94CO2T1, xe2x80x94CONHT1 or xe2x80x94CF3,
A3 and A4 are independently xe2x80x94CN, xe2x80x94CO2T1, xe2x80x94CONHT1, xe2x80x94CF3, xe2x80x94CHO, xe2x80x94COT, xe2x80x94SO2T, xe2x80x94NO2, xe2x80x94T4 or xe2x80x94T5, subject to the proviso that
A3 and A4 are not both T4 or T5,
A5 is H, T1, T2, T4,
D is a radical of the formula 
where
R11 and R51 are independently H, CF3, Cl, Br, xe2x80x94CN, xe2x80x94NO2, xe2x80x94CO2T1, T1, T5, xe2x80x94SO2T1, xe2x80x94SO2T4,xe2x80x94OT1, xe2x80x94OT2, xe2x80x94OT4, xe2x80x94OCOT4, xe2x80x94OCOT4, xe2x80x94OSO2T1 or xe2x80x94OSO2T4,
R21 and R41 are independently H, Cl, Br, xe2x80x94NO2, xe2x80x94CF3, T1, xe2x80x94OT1, xe2x80x94OT2, xe2x80x94OT4, xe2x80x94OCOT1, xe2x80x94OCOT4, xe2x80x94OSO2T1 or xe2x80x94OSO2T4,
R31 is H, Cl, Br, xe2x80x94CN, xe2x80x94NO2, xe2x80x94CF3, xe2x80x94CO2T1, T1, T5, xe2x80x94OT1, xe2x80x94OT2, xe2x80x94OT4, xe2x80x94OCOT1, xe2x80x94OCOT4, xe2x80x94SO3T1 or xe2x80x94SO2T4,
T1 is C1-C8-alkyl which may be substituted by C1-C8-alkoxy, xe2x80x94C1-C8-alkoxy-C2-C5-alkoxy, xe2x80x94OCOT1, xe2x80x94CO2T1, Cl, Br, xe2x80x94CN or T4,
T2 is C2-C8-alkenyl which may be substituted by xe2x80x94C1-C8-alkoxy, xe2x80x94C1-C8-alkoxy-C2-C5-alkoxy, xe2x80x94CN, xe2x80x94CO2T1, Cl or Br,
T4 is phenyl which may be substituted by Cl, Br, T1, OT1, xe2x80x94CF3, xe2x80x94NO2,xe2x80x94CN or xe2x80x94CO2T1,
T5 is oxazole, phenyloxazole, benzoxazole, thiazole, benzothiazole, thiadiazole or thiophene, which may be substituted by Cl, Br, T1, xe2x80x94NO2 and/or xe2x80x94CO2T1, and
X is O.
In very particularly preferred disperse dyes of the formula (V)
A1 is H or T1,
A2 is H, xe2x80x94CN or xe2x80x94CO2T1,
A3 is xe2x80x94CN or xe2x80x94CO2T1,
A4 is A3,
A5 is H or T1,
D is a radical of the formula 
where
R11 and R51 are independently H, Cl, Br, xe2x80x94CN, xe2x80x94NO2, xe2x80x94CO2T1, T1, xe2x80x94OT1 or xe2x80x94OT4,
R21 and R41 are independently H, Cl, Br, xe2x80x94NO2, T1 or xe2x80x94OT1,
R31 is H, Cl, Br, xe2x80x94CN, xe2x80x94NO2, T1, xe2x80x94CO2T1 or xe2x80x94OT1,
T1 is C1-C6-alkyl,
T4 is phenyl which may be substituted by Cl, Br, xe2x80x94NO2 and/or xe2x80x94CO2T1 and
X is O.
Preference is likewise given to dye mixtures containing at least one dye of the formula (I), at least one dye of the formula (IV) and at least one dye of the formula (V).
The dyes and dye mixtures of the invention may be converted into solid or liquid preparations by grinding, for example in a bead mill, in the presence of assistants such as for example dispersants, wetting agents and dustproofers.